William Herschel and the Biggest Telescope of the 18th Century

William Herschel was possibly the greatest astronomer of the 18th Century. He made many discoveries including the finding of Uranus. But his biggest claim to fame was his ability to build telescopes. Over his lifetime he hand-built over 400 telescopes including a giant that was over 40 feet long with a mirror that was almost 50 inches wide.  He paved the way for many astronomers and telescope makers for centuries to come.

He first picked up the pursuit of astronomy as a hobby.  It quite possibly would have remained just a hobby but on one night in 1781 he discovered the planet Uranus and this discovery brought him a lot of fame and enough fortune to give up his normal job as musician. He went on to study astronomy and telescope making full time. He became so enamored by it and by the art of telescope making that he rose to the position of Kings Astronomer and during his lifetime he made telescopes and discoveries of celestial objects that shaped much of the modern science and pursuit of astronomy.

He was born in 1738 and he lived until 1822. During this time he and his sister Caroline devoted many hours and many nights to observing celestial objects and making ever larger telescopes.  His largest telescope was larger than a house, and while it was quite a remarkable instrument, it was cumbersome to use so he used a smaller telescope that was only twenty feet long for most of his serious discoveries and observations.

Some of Herschel’s Discoveries and Accomplishments

·         He discovered a new planet (Uranus) in 1781

·         He built the largest telescope of his time

·         He discovered two satellites of Uranus

·         He discovered two moons of Saturn (Mimas and Enceladus)

·         He discovered two new moons of Jupiter (Titania and Oberon

·         He coined the word asteroid from the Greek

·         He created an extensive catalog of nebulae called the Herschel Catalog which has over 2,500 listings

·         He discovered that most double stars were not optical doubles but actual binary stars that revolved around each other. This was significant because it was the first proof that Newton’s law of gravitation applies to objects outside our solar system.

·         By observing the motion of stars he also discovered the fact that our solar system is moving in space.  And he determined in which direction it is moving.

He built most of his telescopes and used them at his home in Bath England and to this day the home still stands and has been turned into a museum that the public can visit. It is called the Herschel Museum of Astronomy.

His sister Caroline spent many years as his assistant and she would take extensive notes while he observed through the telescope. Eventually she began making observations on her own and became quite a famous astronomer in her own right. She is credited with making many discoveries including eight comets and the M 110 Galaxy which is the second companion galaxy to the famed Andromeda Galaxy.

William Herschel lived in a time when it was not possible to simply buy a telescope. He was forced to build his own. Because of this he advanced both the science of astronomy and the art of telescope making. His largest telescope was the largest in the world for almost 50 years.  Eventually technology improved and it allowed other people to make even larger and better telescopes. Nevertheless Herschel holds a special place in the worlds of astronomy and telescope making as the greatest telescope maker of the 18th century and as one of the greatest observers of all time.